Conventional methods for generating reference indices in the derivation process for temporal direct luma reference index prediction mode need at least three steps (clocks) when both inputs are negative. Processing logic needs to handle the multiple parameters when the parameters do not arrive at the same time. Common processing instructions would be available that are not reused to generate the reference indices given the calculation can be changed.
Existing approaches for determining a minimum positive reference index use the function:MinPositive (a,b)={a; if ((b<0)||((a>=0&&(a<=b)){b; if ((a<0)&&(b>=0))||((a>=0)&&(b>=0)&&(a>b))With such an approach, the output is dependent on the order of the inputs. In particular, the output is asymmetric with respect to the inputs. The result is that on a sequential machine that uses one clock to execute each instruction (e.g., many CPUs), such an approach uses six instructions and therefore 6 cycles to execute:b<0, compare||, logical ora>=0, compare
It would be desirable to implement a processing method and/or apparatus that would reuse process steps to simplify processing.